Process for treating oils



Oct. 22, 1940. u. B. BRAY PROCESS FOR TREATING oILs Filed sept. 25, 1954 10h. NSS

I INVENTOR. v Zlvzc 5 Bray l BY ATTORNEY.

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` 50 through the leaching solvent.

j Paienfedfocf. 22,y 1940 y UNITED t VSTATES PATENT OFFICE Ulric Bray, Palos Verdes Estates, Calif., as-

signor to Union Oil Company of California, Los Angeles, Calif., a'corporation of California Application septemer 25,1934, seria1No.745,417

`.22 claims. (o1, 19e-18) The present `invention relates to an improved process for separating asphalt and/or wax from petroleum oils; The invention relates particularly to` a process for producing lubricating oil 5 by separating impuritiessuch as asphalt and/or waxfrom'oils containing the same.

t Ihave discovered that when a waxy oil is commingled with a solvent or diluent ata reduced t temperature, say 0 F. to 40 F., the waxy oil becomes crystallized or solidies to form a congealed massof oil and wax. Upon continued contact of the solidified oil and wax such as takes place when the solidied particles settle gradually to the bottom of the container of `lli chilled solvent; solution of `the oil in the resulting solvent takes place corresponding to a leach- `ing out `of the oil fractions from the Wax matrix leaving the `wax particles undissolved. This `process distinguishes from former practice in that instead of thewax and oil being rst dissolved `inthe diluent and the wax subsequently crystallized out of solution, `the .waxytoil is first sclidied and solution of the oil takes place so that the oil is leached from the wax without dis` 25 solving any material portion of the wax. The

wax, for the most `partgis obtained in a large or coarse flake-like form which readily settles out or filters' and hence reduces the mechanical difculties normally encountered fromwine dispersion of wax.-4 A small amount `of the crystallized wax may remain in suspension but this can be `easily removed byLiiltration. V t t The` rate of. waxy' oil introduction into the cold solvent is `extremely important since if the .35 rate is toorapid, the sprayed solidified oil and wax willtend to `balla-up or agglomerate into large masses lfromwhich the oil is leached with great difficulty. The rate of 4waxy oilintroduction into the cold leaching solvent will depend largely 40 upon the temperatureof the waxy oil when introduced into the leaching solvent` or in other words, the rate will depend `upon the viscosity of the waxy Voil at the temperature of introduction into `the solvent.A As will be pointed out, oils having low viscosities at the temperature of introduction into the cold leaching solvent crystallize as spongy masses which agglomerate readily at the top of the leaching column;` This spongy mass descends or settles rather slowly `Such oils must necessarily be `introducedrather slowly in order to permit proper leaching and to prevent accumulation and agglomeration at the vtop of the column. Oilshaving highviscosities at the temperature `of introductioni'nto the leaching solvent `crystallize as 4strings or pellets which descend rapidly through the solvent. These oils may be introduced at a `greater rate than the oils of low viscosity provided the height of the column is sufcient to provide adequate leaching of the occluded oil from the crystallized wax.

The rate of oil introduction cannot be given in exact iigures since this will depend uponthe size or height of the leaching column, the ratio of solvent to waxy oil and the character of leach- 10 ing solvent and waxy oil. However, the rate may fbe readily determined'by anyone skilled in the art. When using liquid propane at a temperature of 40 F. as the leaching solvent in a ratio ofapproximately volumes of the propane 15 to one of the waxy oil, I have found that it'requires approximately one hour for the solvent to thoroughly leach out the occluded oil from the wax matrices; Therefore, if the propane is introduced countercurrent to the waxy oil at a 20 rate of 200 barrelsper hour, `the oil should be sprayed into the top of the leaching` column at a `rate of not in excess of forty barrels per hour in `.order to provide a leaching time of one hour. In the particular case, `the [oil sprayed had a 25 viscosity of less than 500 seconds Saybolt Universal at F, and the waxy oil solidied in flaky form when sprayed into theV cold solvent. l It is obvious that if the oil had been solidified, by the leaching solvent as strings or pellets, the 30 `leaching time would begreater.v Also, if the .of the leaching column; The wax structure remains practically in the shape as when the waxy oil is first crystallized at the top of thecolumn. However, due to the fact that the cementing oil is removed, the crystallized Wax particles are extremely'fragile and` will break into nely divided particles' if the same are subjected to severe agi- 50 tating conditions.` Such nely divided wax particles are difficult toseparate from the oil by suchmeans as settling; or filtering.

It` is thus important to` `prevent substantial working of the solidied particles at the top 5 of the leaching column so as to prevent agglomeration and at the bottom after the oil has been leached out of the crystallized structure so as to prevent rupture of the crystallized wax particles.

I prefer to introduce the oil into the cold solvent in such manner that leaching of the oil by the solvent takes place rapidly. I have discovered that if the cil is introduced into the cold solvent as a spray or fine streams, solidication takes place upon the surface of the cold solvent as ilat buttons or flakes. The solvent may then readily dissolve out the oil from the solidied particles leaving wax matrices which have been thoroughly washed from oil 4and which settle rapidly to the bottom of the decanter in which the leaching operation takes place. The size of the solidified waxy oil particles will, of course, depend upon the leaching conditions desired, that is, the time desired tocomplete the leaching operation, which will, in turn, depend upon the character of the waxy oil and the solvent to oil ratio during leaching. Preferably, however, the size of the solidified oil particles should not .be too thick, since the leaching time increases considerably. I have found that sufficiently rapid leaching will be obtained when the waxy oil is solidiiied in thicknesses substantially not greater than 1/4 in. atits smallest dimension. I may solidiiy the waxy oil as hat buttons orV flakes or pellets 1A; in. thick or-as long strings 1/4 in. in diameter or even as sheets 1/4 in. thick.

While I may operate by spraying the `oil at a low viscosity directly into .the refrigerating diluent, I preferably operate in such m-anner as to rst obtain good crystallization of the wax in the oil and follow this by leaching out the occluded oil. I may accomplish this by chilling the oil, for example, to below its pour point in the absence of a ldiluent fand subsequently spr-ay or otherwise introduce the crystallized wax and oil into the cold leaching diluent. If desired, `the waxy oil may be subjected to a digesting operation at a low temperature preferably at a temperature below the pour point of the waxy -oil kso as to permit goodv crystallization of .the wax in the oill and subsequently leach out the occluded oi-l. rIhe leaching temperature or temperature of the leaching solvent may then be either at 4the -ltemperature of' `digestion or slightly below. By operating in this manner substantially little or no wax will be ydissolved in the leaching d-iluent and thus less difficulty will be encountered with subsequent recrystallfization of wax in nely dispersed form and effects of solvation of oil in the wax. f

Another method for preparing the waxy oil prior to leaching resides in chilling fthe waxy oil to below its pour point, .t-hen working .the waxy oil to break up Vthe gel and form la fluid mass and repeating this operation of chilling and breaking up .the gel until substantially all of fthe wax has been crystallized into good wax crystals. This mixture may then .be sprayed or introduced as small particles into the lcold leaching solvent. It will be observed that when the waxy 4oil is chilled `to below its pour point, a portion of the wax crystallizes out of the oil and the mass becomes fa gel. This gel may be made readily fluid again by working suchas by gently stirring the mass. However, when lthe gel is broken, the crystallized wax will not redissolve in the oil. By repeatingthis voperation of Ichilling to, say a lower Itemperaturathe mass will again become a gel forming new wax crystals which may again be broken or rendered fluid by further working.

After a number of such operations of chilling and breaking .the gel, ,the wax present in the oil may be substantially all crystallized into large wax crystals. This mixture may then be sprayed or otherwise introduced into the cold leaching solvent.

I have observed that the character of the waxy oil regarding its viscosity .at the temperature of introduction into .the cold leaching solvent and also the character of lthe leaching solvent itself iniluences the character of .crystallization in the solvent. However, when employing normally liquid or substantially non-volatile solvents such as oasinghead gasoline, hex-ane, pentane and .the like, an roil of any viscosity whether high or low, will crystallize in .the cold leaching solvent in the form of strings or pellets. On fthe other hand, when waxy oils are sprayed into highly volatile or liqueed normally gaseous hydrocarbon sol ven-ts, for example propane, .the viscosity of the waxy oil at Ithe temperature of introduction will determine whether .the waxy oil will crystallize as strings or pellets or as a spongy mass. If the viscosity of the oil is low, for example, below 500 seconds Saybolt Universal at the temperature of spraying into the cold leaching solvent, crystallization takes place as a spongy mass. This is perhaps `due .to the fact .that las the sprayed particles contact -the cold leaching solvents, the

rsprayed particles solidify as bubbles containing bolt Universal or higher at the 'temperature ,of

introduction, are sprayed into such volatile solvents, crystallization takes place as strings or pellets. The viscosity of the oil can Ibe low,either due to its intrinsic nature or because of predilution with a diluent or because of its being heated to an elevated temperature. The viscosity may be high due alsol to its intrinsic nature or because of precooling prior to spraying into the cold leaching solvent.

Whether a spongy mass or strings or pellets is desirable or not depends upon conditions of the leaching operation. A spongy mass is desirable where conditions of the leaching lare quiescent because leaching takes place more rapidly due to the thinner sections of the crystallized oil. rIhus, when leaching in solvents of high vola-- tility, itis preferable to maintain the solvent particularly in the lower part of the leaching column in a substantially quiescent state. This may be accomplished by imposing superatmospheric pressure on the solvent during the leaching operation. Pressure may ibe'imposed by introduction of an extraneous gas which is insoluble in the leaching solvent or which will not liquefy aft .the

low .temperatures existing in the leaching column.

Thus, I may use air, carbon dioxide or other gases under pressure sufcient to suppress substantial boiling of the leaching solvent. I may also suppress substantial boiling fat the lower part of the leaching column by controlling Ithe escape of v-aporized leaching solvent, such vaporization 0ccurring when the relatively warm waxy oil lcontacts .the cold leaching solvent. Thus, by controlling the operati-on of a valve positioned on top of the leaching column so as .to maintain pressure on the liquid, I may suppress substantial boi-ling :at point-s below .the upper portion of the column. A small amount of boiling at the top of the column is not detrimental to the success of operation of the process particularly when the rate of oil introduction is controlled fairly low so as to` prevent `agg'lomeration of crystallized waxy oil. However, agitation must not `be severe `after a substantial amount of oil beenl leached out of the crystallized structure, otherwise, ,the Wax crystals will break up into finely dispersed particles which are dificulit lto separate trom the oil solvent solution by settling and the like.

When leaching in solvents of low volatility or substantially. non-volatile solvents, the leaching may be accomplished with gentle or slow agitation. This is for the purpose of presenting new surfaces to the leaching solvent and prevent the solidified pellets or strings from massing at the bottom of the leachingrcolumn. Gentle or slow agitation is desirable under these conditions for the reason that the crystallized strings or pellets settle rapidly to the bottom of the leaching column and, therefore, must necessarily be agitated for `the purpose of permitting the leaching solvent to dissolve the oil. However, the agitation must not be so severe that the crystallized masses will break up into finely dispersed wax crystals. This precaution is particularly necessary, as stated above, during the last stages of the leaching operation since theleached particles comprise fragile wax crystals substantially in the shape originally crystallized in the solvent but from which the occluded oil has been leached out.

whereas when in an unbroken state, the crystals settle readily to the bottom of the decanter. The agitation may be accomplished' by providing a stirring device in the leaching column as is Well known to those skilled in the art. `The stirrer is preferably'operated very slowly, merely suflicient to churn the crystallized masses. In a countercurrent leaching process` where the Oil is introduced into the top of a leaching column and solvent at the bottom, the agitation accompanying the introduction of solvent at the bottom of the leaching column may be sufficient to prevent the strings or pellets of crystallized oil from forming large massesito prevent the leaching solvent from producing the desired results.

In general, the character of the leaching solvent is one which has a good solvent power for oil but not for the wax at low temperatures. As leaching solvents, I may employ any of the liqueiied normally gaseous hydrocarbons, such as ethane, propane, butane, iso-butane, or mixtures thereof. I may also employ'such normally liquid hydrocarbon solvents as pentane, hexane, etc., casinghead gasoline, naphtha, etc. At low temperatures, the hydrocarbon solvents readily dissolve the oil from the crystallized wax oil but dissolve substantially none of the wax. Other solvents which may be employed comprise alcohol, ether, mixtures of alcohol and ether, acetone, benzol or mixturesof acetone and benzol, and chlorinated normally gaseous hydrocarbons such as methylene chloride and dichlor ethylene.

When employing liquefied `normally gaseous hydrocarbons, the temperature of the leaching solvent is preferably reduced by vaporizing a portion of the solvent under reduced pressure to substantially the boiling point of the solvent. Normally liquid solvents may be chilled by circulating them in indirect heat exchange Ywith a refrigerating medium, such as cold brine or by commingling the-normally liquid solvent with aliqueiied normally gaseous hydrocarbon such as liquid propane and effect the chilling by vapor- Such crystals break readily with substantial agitation into finely dispersed particles izng the normally vgaseous hydrocarbon under reduced pressure. To effect the chilling of the normally liquid solvent, other liquefied normally gaseous materials may be employed such as ammonia, liquid sulphur dioxide, methyl chloride, carbon dioxide and the like which exert va refrigerated effect by reducing the ,pressure and vaporizing the liquefied normally gaseous material.

Another feature of my invention resides in premixing the waxy oil with wax anti-solvents prior to introduction into th-e leaching solvent. Thus, I may commingle the waxy oil either at, below or above the pour point of the waxy oil and subsequently spray or otherwise introduce the mixture into the leaching solvent.` If desired, I may mix the waxy oilwith the wax anti-solvent at a temperature above the pour point of the oil, then precool the mixture to obtain good crystallization of the wax in the mixture and subsequently introduce the chilledmixture into the leaching solvent. I may first obtain the desired crystallization of the wax inv the oil and subsequently dilute the chilled oil with a Wax anti-solvent and then leach out the occluded oil. As wax anti-solvents I may employ naphtha. preferably having a boiling range between 200 and 300 F., alcohols such as methyl, ethyl, propyl or butyl or mixtures thereof, chlorinated light hydrocarbons such as dichlorethylene and trichlorethylene, mixtures of benzol and the like and acetone or other ketones, mixtures of benzol and the like and butanol or other alcohols, liquid sulphur dioxide, aniline, chloraniline, nitrobenzol, dichlorethyl ether, methyl formate, phenol, cresylic acid. Some of these anti-solvents are also good leaching solvents as, for example, benzol and alcohol. When using such solvents it may be desirable to mix the waxy oil with a small amount of the solvent, obtain good crystallization by chilling and then effect` the leaching in a larger volume of the same solvent. In the case of mixtures of acetone and benzol or toluol as wax anti-solvents, it may be desirable to use acetone, perhaps with small amounts of benzol or toluol, for the predilution and obtaining good crystallization o-f wax prior to leaching and subsequently effect the leaching` in benzol or toluol.

It is thus an object of my invention to accomplish dewaxing of waxy oils by spraying the waxy oil into a cold leaching solvent so as to obtain solidiiication of the waxy oil and subsequently leach out the occluded oil from the solidified masses to leave a substantially oil-free wax. It is an object of the invention to control the size of the oil stream introducedinto the cold leaching solvent so as to obtain crystallized oil particles which may be readily leached by means of the leaching solvent.`

An important object of the invention is to employ as leaching solvents, such materials which have a good solvent power for oil but not for wax at low temperatures.

It is a particular object of the invention to employ a liqueed` normally gaseous hydrocarbon such as propane as the leaching solvent and to prevent ebullition in the lower portion of the leaching column so as to prevent breaking of the wax matrices into finely dispersed particles. In other words, it is an object of the invention to produce suiiiciently large wax crystals or particles which may be readily removed from the oil solvent solution by settling.

Itis another object of my invention to accomplish good crystallization of wax in the oil and subsequently leach the occluded oil from the wax by means of a solvent to leave a wax matrix substantially free from oil which may be readily separated from the oil solvent solution by settling.

Another object of the invention resides in commingling the waxy oil with a Wax anti-solvent and subsequently leach out the oil by a cold solvent adapted to dissolve the oil but not the wax at a low temperature.

Another object of the invention resides in commingling the waxy oil with a good wax anti-solvent and obtain good crystallization of the wax in the presence of a wax anti-solvent prior to leaching and subsequently leach out the oil from the mixture in the presence of a solvent which has a good solubility for the oil but not the wax. Other objects and features of my invention will be apparent from the following description of the drawing which is not to be considered as limiting:

Referring to the drawing, the waxy oil in tank I at a temperature above its congealing` point is withdrawn through line 2 controlled by valve 3 and pumped by pump 4 through line 5 and valve 6 through spray head 'I where it is passed countercurrent to a leaching solvent at a low temperature as will be further described.

Instead of spraying the waxy oil directly into the leaching column, I may iirst subject the waxy oil to a prechilling operation by closing valve 6 and opening valve 9 on line I0 and passing the waxy oil into mixer or chiller II which is provided with a propeller agitator and scraper I 2 operated by pulley I4 connected to a suitable source of power not shown. Chamber II may be operated either as a mixing chamber or as a chilling chamber or both. Chilling in chamber I I may be accomplished by expanding a refrigerating material through jacket I5 such as liquefied normally gaseous hydrocarbon as liquid propane withdrawn from storage tank I6 via line I'I controlled by valve I1 and pump I 9 which forces the liquid propane through line 20 and pressure reduction valve 20 into jacket I5. The vaporized propane leaves jacket I5 via line 22 and valve 22 and passes into line 23. The temperature in jacket I5 may be controlled by operation of valve 22 which controls the pressure in the jacket. The vaporized propane passing into line 23 from all apparatus in which propane is Vaporized is recovered by compressing in compressor 24 where the pressure on the propane gases is increased and then passes via line 25 to condenser 26 where the compressed propane is liquefied which then flows through 2'I into propane storage tank I6. Instead of expanding 'liquid propane into jacket I5 to effect the desired refrigeration, I may expand other liquid materials which are normally gaseous under ordinary temperatures and pressures and which accomplish a refrigeration when expanded. Such materials may comprise liquid ammonia, liquid sulphur dioxide, liquid carbon dioxide, methyl chloride and the like. If desired, I may circulate a'cold liquid through the jacket to el'ect the desired refrigeration. This may comprise the dewaxed cold solvent oil solution prior to removal of the solvent from the oil. If desired, a small amount of the liqueiied normally gaseous lhydrocarbon may be mixed with the waxy oil and chilling accomplished by vaporizing the solvent under reduced pressure.

The extent of refrigeration of the waxy oil will depend upon the particular conditions under which the operation is desired to be carried out.

For example, I may merely chill the waxy oil to slightly above its pour point, say 120 F. for an oil having a viscosity of 240 seconds Saybolt Universal at 100 F., and then spray the waxy oil into the leaching solvent, or I may chill to below the pour point of the oil as, for example, 60 F., prior to the leaching operation'. In connection with the latter operation, the waxy may be subjected to suiiciently low temperatures to accomplish crystallization vof the lwax in oil prior to leaching. One desirable method of operation is to effect the precrystallization of wax gradually by chilling to, say the pour point of the oil, 115 F. for example, and obtaining some crystallization of the wax,l the oil being substantially in the form of a gel. This gelmay be broken by slowly agitating the gel such as by means of agitator I2 to obtain a fluid mass. The partially chilled mass may then be further chilled to a lower temperature than the pour point of the oil, say 40 F., to obtain further crystallization of the wax and gelling of the oil which may againbe broken by agitator I2. After substantially all of the wax has been crystallized and the gel broken in such manner as to not obtain substantial disruption of the wax crystals, the mass may be introduced into leaching column 8 via line '28 controlled by valve 28' and pump 29 which forces the chilled mass through spray 'I.

If desired, the waxy oil may be gradually chilled without substantial agitation to low temperatures, for example F., to crystallize substantially all of the wax from the oil and allowed to digest at this temperature for a period of time until good crystallization of the wax has resulted. Then it may be commingled with a diluent introduced into mixer I I via line 30 controlled by valve 30 so as to obtain a fluid porridge-like mass which may be readily pumped through the spray head 7. The admixture of diluent as, for Iexample, naphtha, may be eiected by means of agitator I2. However, this admixture is preferably under slow agitation so as not to break the wax crystals.

In leaching column 8, the sprayed oil upon contact with the cold leaching solvent at the top of the leaching column, is immediately solidified and in passing countercurrent to leaching solvent introduced at the bottom of the column, the solidied oil is dissolved in the leaching solvent, leaving a wax matrix at the bottom of the leaching column substantially free from oil.

yWhere anormally gaseous liquefied hydrocarbon, such as liquid propane, is employed as the leaching solvent in column 8, the liquid propane is withdrawn from propane storage tank I via line I'I controlled by valve Il to pump I9 which forces the propane through line 3l controlled by valve 3l into propane chiller 32 where a portion of the liquidi propane is Vaporized by opening valve 33 on line 33. The vaporized propane being released through valve 33 `passes through line 33 into line 23. By reducing the pressure in chiller 32 to substantially atmospheric, the temperature of the remaining propane will be 'lowered to substantially 40 F. The propane in chiller 32 at -40 F. is withdrawn Via line 34 controlled by valve 34 and pumped by pump 35 into the bottomof the leaching column 8 via a perforated spider 36.

The amount of leaching solvent introduced into the column will depend upon the character of the solvent and the character of the waxy oil. `I have obtained good results when using a liqueed normally gaseous hydrocarbon, such as liquid propane', as the leaching. solvent with as crystallization o-f the wax and subsequently passed into the leaching column.

' When employing wax anti-solvents, it isdesired to recover the wax anti-solvents from the dewaxed oil and from the separated wax as a separate fraction from the diluent employed.

This may be accomplished by condensing the vaporized diluent and wax anti-solvent in evaporators 4T and 68 to obtain condensation of the Wax anti-solvent if such has a higher boiling point than the diluent or condensation of the diluent if the boiling point of the diluent is higher than that of the wax anti-solvent and then collecting the condensate as a separate fraction. The unvaporized material may then be liqueed by compression and cooling if this material comprises a liqueed normally gaseous hydrocarbon diluent.

The following represent examples of the operation o-f the process forming the subject matter ofy my invention:

Example 1 A raiiinate produced by extracting a waxy distillate with a mixture of liquid sulphur dioxide and benzol and having an A. P. I. gravity of 31.5, a viscosity of 50 seconds Saybolt Universal at 210 F.,\a`pour point of 120 F. and a wax content of approximately 25% was sprayed at a temperature of about F` which is slightly above the pour point of the waxy oil into cold propane. tom of the leaching column countercurrent to the waxy oil and was at a temperature of 40 F. The amount of propane introduced into the leaching column was in the ratio of about 7 volumes of propane for every volume of waxy oil sprayed into the column. After washing the wax countercurrently in the leaching column and ltering theoil solvent solution decanted at the top of the column to remove a small quantity of suspended Wax, the solvent was distilled .from the oil, the recovered oil had a pour point of 0 F., an A. P. I. gravity'of 29, a viscosity of 53 seconds Saybolt Universal at 210 and was recovered in a yield of 72%. The wax, after vafporizing the propane, had a melting point of F. and was recovered in a yieldof 27%.

Example 2 n A raw distillate from a Santa Fe Springs crude having an A. P. I. gravity of 20 and a'viscosity of 70 seconds` Saybolt Universal .at 210 F. and a pour point of .115 F. was chilled to a tempera-ture of 40 F. in a device such as mixer il and mechanically agitated to break up the ywax gel structure giving a porridge-like mass which was then sprayed into cold propane at 40 F.` Propane at a temperature of 40 F. in a ratio of about 5 volumes to one of the waxy oil was introduced into the bottom of the leachingcolumn in the manner heretofore described. A yield of oil equal to 80% of the original was recovered having a Viscosity of '74 seconds Saybolt Universal at 210 F and a pour point of 0 The recovered wax had a melting point of 128 F. and was obtained in approximately 20% yield.

Example 3 The same distillate as in Example 2 was mixed with an equal volume of a mixture of 50% acetone and 50% toluol and the mixture cooled to 10 F. with slow agitation.. This mixture was then passed into cold propane and extracted with 5 volumes of propane at a temperature of 15 Propane was introduced into the bot- F. to one volume of the waxy oil. The recovered oil had a pour point of 5 F., a viscosity of '72 seconds Saybo-lt Universal at 210 F. and was recovered in a yield of 81%. The wax had a melting point of abou 129 in a yield of about 19%.

The foregoing exemplary description of my invention is not to be considered as limiting since many variations may be made within the scope of the following claims by those skilled in the art withoutdeparting from the spirit thereof.

I claim:

1. A process for dewaxing oils which oomprises congealing a waxy oil by contact with a relatively large body of cold solvent capable of dissolving oil at the low temperature of operation but not substantial quantities of wax and subsequentlyextracting the oil in said congealed waxy oil by means of said solvent to leave a v wax matrix substantially free from oil, separat- 2 ing the wax matrix from the oil dissolved in said. solvent and separating the cil from the solvent.

2. A process for dewaxing oils which comprises spraying waxy oil into a relatively large body of cold solvent capable of dissolving oil at the low 2 temperature of operation but not substantial quantities of wax, solidifying said sprayed oil by means of said cold solvent to form a plurality of congealed particles of wax andoil, extracting the occluded oil from said congealed 3 particles by means of said cold solvent to leave wax matrices substantially free from occluded oil without dissolving substantial amounts of wax, removing the oil solvent solution from the wax matrices and separating the solvent from the oil. 3

3. A process as in claim 2 in which the solidified sprayed oil particles are countercurrently extracted with a cold solvent capable of dissolving oil at low temperaturesbut not the wax.

` 4. A process as in claim 2 in which the cold 4 solvent comprises a liquefied normally gaseous hydrocarbon. l

5. A process as in vclaim 2 in which the cold solvent comprises liquid propane.

6. A process for dewaxing oil which comprises 4 introducing a waxy oil into a relatively large body of cold solvent capable of dissolving oil at the low temperature of operation but not substantial quantities of wax, congealing and solldifying said oil by contact vwith said cold solvent, allowing 5 said congealed and solidified oil to contact said cold solvent for sufficient time to permit said solvent to leach occluded oil in said congealed and solidified waxy oil and to leave a solidified wax matrix substantially free from occluded oil, 5

separating the oil dissolved in said solvent from the wax matrix and separating the solvent from the oil.

'7. A process for dewaxing oil which comprises g commingling waxy oil with a wax anti-solvent 6 and subsecuently introducing said mixture into a relatively large body of cold solvent capable oi dissolving oil and wax anti-solvent at the low temperature of operation but not substantial quantities of wax, freezing and solidifying saidc mixture kby means of said cold solvent, allowing said frozen mixture to contact said cold solvent for sufficient time to permit said solvent to leach out the occluded oil in said frozen mixture and to leave a solidied wax matrix substantially free from occluded oil, separating the oil dissolved in said cold solvent and wax anti-solvent from the wax matrix and separating said solvents from said oil.` f p 8. A process for dewaxing oils which comprises 7 F. and was recovered 5 cooling a waxy oil to a temperature sufficiently low to permit crystallization of wax in oil,`mixing said cooled waxy oil with a'wax anti-solvent and subsequently leaching outthe oil and wax antisolvent from` the wax crystals by means of a solvent capable of dissolving the oil but not the wax crystals at the lowtemperature of operation, separating the solution Yof oil andfsolvents from the wax crystals and separating the; solvent from the oil.

9. A process forldewaxing oil which comprises commingling a waxy oil`withY a Wax anti-solvent,

cooling the mixture to atemperature suiciently low tok obtaincrystallization of wax insaid mixture and subsequently `leaching out the oil and wax anti-solvent fromthel wax crystals by means of a solvent capable of dissolving the oil and wax anti-solvent `butlnol', the wax crystals at the low temperatureof operation, ,said leaching being ac.- complished without substantial agitation and without `separation of oil and wax antisolvent from the crystallized wax prior to the contact of leaching solvent with said oil, wax crystals and wax anti-solvent, separating the solution of oil and solvents from the wax crystals and separating the solvent from the oil.

l0. A process for `devvaxing oilswhich comprises spraying a waxy oil into the top of a leaching column containing a relatively large body of cold solvent capable l of dissolving oil atthe low temperature of a operation but not substantial quantities of wax, introducing cold leaching solvent into the bottom of said leaching column, freezing and solidifying said waxy oil by means of said cold solvent, allowing said frozen oil to contact said cold solvent for a sufficient length of time to permit said solvent to leach out occluded oil in said frozen waxy oil and leave a solidiiied waxmatrix substantially free from occluded oil at the lower portionof said `leaching column, preventing substantial agitationof said wax matrix in the lower portion of said leaching column, removing the wax matrix from the lower portion of the said leaching column and the solution of oil and solvent from the top of said leaching, iiltering said oil-solvent solution to remove the entrained wax particles and separating the solvent from the oil.

11. A process for dewaxing oils which coml prises spraying a wax-oil mixtureinto a relatively large body of cold solvent capable of dissolving oil at the low temperature of operation but not substantial quantities of wax, said wax-oil mixture being sprayed into said cold solvent at a temperature and viscosity sufficient to solidify the sprayed particles of wax-oil mixture in the form of flakes, extracting occluded oil from the solidified wax-oil flakes by means of said coldA solvent to leavewax structures substantially free from oil, removing the oil and solvent from the wax structures and separating the solvent from the oil. a

12. A process for dewaxing oils which comprises spraying a wax-oil mixture into a relatively large body of cold solventcapable of dissolving oil at the low temperature of operation but not substantial quantities of wax, said wax-oil mixture being sprayed into said cold solvent at a temperature and viscosity suilicient to solidify the sprayed particles of wax-oil mixture in the form of strings or pellets, extracting occluded oil from the solidified wax-oil strings or pellets by means of said cold solvent to leave wax structures substantially free from oil without dissolving substantial' amounts of wax, removing the oil and solvent from the wax structures and' separating the solvent from the oil. '13. A process for 4dewaxing oils which comprises spraying waxy oil while in a heated and suiiiciently fluid state into a relatively large body of cold solvent capable of dissolving oil at the low temperature of operation but not substantial quantities of wax, solidifying said sprayed oil by means of said cold solvent to form a plurality of frozen particlesof wax and oil, extracting the occluded oil from said frozen particles by means of said cold solvent to leave wax matrices substantially free from occluded oil without dissolving substantial amounts of wax, removing the oil solvent solution from the wax matrices and separating the solvent from the oil.

14.` A process for dewaxing oils which comprises precooling a waxy oil to a temperature slightly above its pour point, congealing and solidifying the thus precooled oil by introducing the same into a relatively large body of cold solvent capable of dissolving oil at the low temperature of operation but not substantial quantities of wax and subsequently extracting the oil contained in said congealed and solidified waxy oil by means of said solvent to leave wax structures substantially free from oil, separating the wax mixture from the oil dissolved in said s01- vent and separating the oil from the solvent` Il5. A process for dewaxing oils which cornprises gradually cooling a wax-oil mixture to a temperature sufficiently below the pour point of the wax-oil mixture to crystallize wax in the oil and subsequently contacting the chilled mixture with a relatively large body of leaching solvent at a sufficiently low temperature lower than said aforementioned temperature, further to -congeal and solidify the wax-oil mixture said body of solvent at said low temperature being capable ci dissolving oil but not substantial quantities of wax, leaching the oil from the wax crystals by means of said leaching solvent, separating oil and solvent from the wax crystals and separating the solvent from the oil.

164A` process for dewaxing oils which comprises cooling the wax-oil mixture to a temperature approximating the pour point of the waxoil mixture and to form a gel, agitating the waxoil gel to obtain a iiuid mass, contacting said fluid mass with a relatively large body of leaching solvent at a sufficiently low temperature lower than said last mentioned temperature further to congeal and solidify the wax-oil mixture said body of solvent at said low temperature being capable of dissolving oil but not substantial quantities of wax, leaching the oil from the Wax crystals by means of said leaching solvent, separating oil and solvent from the wax crystals and separating the solvent from the oil.

i7. A process for dewaxing oils which comprises cooling the wax-oil mixture to a temperature approximating the pour point of the waxoil mixture and to form a gel, agitating the waxoil gel to obtain a fluid mass, cooling said fluid mass to a temperature lower than said aforeand solvent from the wax crystals and separating the solvent from the oil.

18; A process for dewaxing oils Awhich comprisesgradually cooling `the wax-oil mixture to a substantially low temperature and allowing said cooled mixture to digest at said low temperature to crystallize substantially all of the wax contained in saidmixture into large wax crystals, commingling said digested mixture while slowly agitating the mixture with a solvent to obtain a iiuid and pumpable porridge-like mass and subsequently contacting said last mentioned mixture with a relatively large body of leaching solvent at a temperature sufficiently low to congeal and solidify -the wax-oil mixture said body of solvent at said low temperature being capable of dissolving oil but not substantial quantities of wax, leaching the oil from the congealed and solidied mixture to leave wax crystals substantially vfree from oil, removing the oil and solvents from the wax crystals and separating the solvents lfrom the oil.

19. The process of separating a hydrocarbon oil-wax mixture into solid constituents and liquid constituents, which comprises diluting said mixture with a solvent liquid, cooling the diluted mixture to effect crystallization of Wax to form a wax mass containing less than substantially 10% by volume 'of solid wax and displacing from said wax mass, without substantial agitation thereof, the liquid constituents of said mass with a displacing liquid.

20. The method of separating oil from an oilwax mixture which comprises adding a diluent to the oil-wax mixture, chilling the diluted oil- Wax mixture to obtain crystallization of the wax in the mixture, introducing the chilled diluted oil-wax mixture into the upper portion of a large body of chilled propane maintained in a settling zone, introducingchilled propane into the lower portion of said settling zone, withdrawing a propane oilsolution from the top of said settling zone, and withdrawing a Wax slurry from the bottom of said settling zone.

21. A process for dewaxing oils which comprises cooling a waxy oil to a temperature suciently low to obtain crystallization of Wax in the cooled mixture, and subsequently leaching out the oil from the wax crystals by means of a solvent capable of dissolving the oil but not the wax crystals at the low temperature of operation, said lleaching being accomplished without substantial agitation and' Without separation of oil from the crystallized wax prior to the contact of leaching solvent with said oil and wax crystals, separating the solution of oil and solvent from the wax crystals and separating the solvent from the oil.r

2,2. A method for separating oil from wax which comprises forming a body of oil and solidied wax at a temperature at which the wax is solid and separating the oil from the solidified wax in said body by washing said wax without prior separation of a substantial portion of oil from saidbody before contact with the Washing liquid, said liquidlbeing one. in which said wax is not substantially soluble but said oil is sub stantially soluble at the temperature of said washing, moving said Aliquid through said Wax body Awithout any substantial agitation of said oil. V

' ULRIC B. BRAY. 

